Mary Lou Williams (born Mary Elfrieda Scruggs; May 8, 1910 – May 28, 1981) was an American jazzpianist, arranger, and composer. She wrote hundreds of compositions and arrangements and recorded more than one hundred records (in 78, 45, and LP versions). Williams wrote and arranged for Duke Ellington and Benny Goodman, and she was friend, mentor, and teacher to Thelonious Monk, Charlie Parker, Miles Davis, Tadd Dameron, Bud Powell, and Dizzy Gillespie.

The second of eleven children, Williams was born in Atlanta, Georgia, and grew up in the East Libertyneighborhood of Pittsburgh, Pennsylvania